Perspective on synthesis of high-energy-density fuels:From petroleum to coal-based pathway

High-energy–density(HED)fuel is specifically pivotal to improve the performance of volume-limited aircrafts.The widely used HED fuels composed of polycyclic hydrocarbons are mainly synthesized from petroleum feedstocks.In order to ensure abundant supply,alternative resources such as coal should be considered.Herein,we summarize the synthesis methods and properties of typical HED fuels by using petroleum-derived cyclopentadiene(CPD)as key feedstock through dimerization,cycloaddition,hydrogenation and isomerization/photoisomerization reactions,and then propose a blueprint for synthesizing HED fuels from coal.The method to produce CPD from coal is analyzed and feasibility is demonstrated according to theoretical calculations and reported results.This review provides a novel route for synthesis of HED fuels from coal.

Joint power control and relay selection scheme for cognitive two-way relay networks

A joint power control and relay selection scheme is considered for a cooperative and cognitive radio system where a secondary network shares spectrum with the primary network. In the secondary network, two secondary users （SUs） communicate with each other via an assist relay. The main point is to provide the best system performance to SUs while maintaining the interference power at primary user （PU） under a certain level. Using convex optimization, a closed-form solution is obtained when optimizing the power allocation among the two nodes and relay. Based on this result, a joint power control and relay selection scheme with fewer variable dimensions is proposed to maximize the achievable rate of the secondary system. Simulation results demonstrate that the sum rate of the cognitive two-way relay network increases compared with a random relay selection and fixed power allocation.

Framework Zr Stabilized PtSn/Zr-MCM-41 as a Promising Catalyst for Non-oxidative Ethane Dehydrogenation

Non-oxidative ethane dehydrogenation is a promising route to produce ethene.Herein,PtSn supported catalysts were investigated to achieve better ethane dehydrogenation performance by introduction of different Zr promoters,i.e.,framework Zr and ZrO_(2),to mesoporous MCM-41.In-situ XRD,TEM and CO chemisorption show that aggregation of metal particles and phase segregation of Pt_(3)Sn to Pt and PtSn_(3) at high temperature occur for PtSn/M,leading to bad ethane dehydrogenation activity.Strong interaction be-tween ZrO_(2) and PtSn species,as proved by XPS,results in restrained metal particles,which promotes the initial reactivity.However,Pt phase generated on surface is disadvantageous for the desorption of produced ethene as indicated by CO-IR and C_(3)H_(6)-TPD,and pyridine-IR and NH_(3)-TPD indicate strong acidity generated.Both deactivate the catalyst rapidly by deep dehydrogenation and coking.Moderate interaction between PtSn species and Si-O-Zr with much weaker acidity is formed when framework Zr is incorporated into MCM-41,which benefits the dispersion of metal particles,formation of Pt_(3)Sn/Pt species and stabilization of metal species from phase segregation.Outstanding initial ethane conversion and ethene selectivity of ca.99%were achieved for the optimal PtSn/ZrM,which is more coking-tolerant and stable by generating graphitic carbon mainly on support instead of active metals.